1. Technical Field
The present inventive concepts relate to an image sensor.
2. Description of the Related Art
An image sensor is a semiconductor device that converts an optical image into an electrical signal. That is, the image sensor is a semiconductor device that converts electric charge, received as a light signal and converted into a voltage signal, to pixels that are displayed on an image. In general, contemporary image sensors may be classified as charge coupled device (CCD) image sensors and complementary metal oxide semiconductor (CMOS) image sensors.
With the continued advancement of computer and communication technologies, CMOS image sensors have come to enjoy widespread use in various fields such as digital cameras, camcorders, game players, security cameras, medical micro cameras, and robots. As CMOS image sensors continue to become more highly integrated and miniaturized, the size of a pixel serving as a unit to represent imaged information continues to become further reduced.
A unit pixel of a contemporary CMOS image sensor commonly includes a photoelectric conversion unit and a charge transfer unit. The charge transfer unit transfers electric charge generated by photoelectric conversion performed on incident light in the photoelectric conversion unit, to a charge detection unit. Meanwhile, the CMOS image sensor includes an active pixel region and an optical black region. The active pixel region receives incident light and converts the incident light into an electrical signal. The optical black region blocks inflow of light and thus provides a reference of a black signal, representing the absence of light, to the active pixel region.